Mr. Moose was a puppet character, in the form of a moose, on the children's television show Captain Kangaroo. He is best known for riddles and knock-knock jokes that resulted in hundreds of table tennis balls cascading from above and hitting the Captain in the head and he laughed at him.
In 1998 Mister Moose & the Captain Kangaroo gang returned with an upgrade, airings on FOX Kids & Fox Family with a spinoff show featuring Mister Moose called Mister Moose's Fun Time.
In "Hell Comes to Quahog", when Joe Swanson sends the last ping-pong ball out the window, Peter Griffin says he will get some more from Moose. While doing so, he sets up a knock-knock joke from him, at the time very weary.